1. Technical Field
The present invention relates to a memory device, and more particularly, to a phase-change random access memory device and a method for manufacturing the same.
2. Related Art
In general, a phase-change random access memory (PRAM) device stores data using a difference in resistance between an amorphous state and a crystalline state due to a phase change of a chalcogenide compound.
FIG. 1 is a cross-sectional view illustrating a conventional phase-change random access memory device, and FIG. 2 is a photograph showing inclining of diode patterns in the conventional phase-change random access memory device.
Referring to FIG. 1, in the conventional phase-change random access memory device, metal contacts 120 are formed on a semiconductor substrate 110 using a metallic substance, and diodes 140 are formed on the metal contacts 120.
In this regard, when the diodes 140 of the conventional phase-change random access memory device may be formed of polysilicon, the adhesion force between the metal contacts 120 formed of the metallic substance and the diodes 140 formed of polysilicon becomes poor. In order to address such a feature, an ohmic contact layer 130 is formed using titanium nitride (TiN).
However, in the conventional phase-change random access memory device, titanium nitride (TiN) constituting the ohmic contact layer 130 is likely to be degraded in a subsequent annealing process, causing a problem in the interface between the titanium nitride (TiN) and polysilicon. Consequently, as shown in FIG. 2, when etching the patterns of the diodes 140 or performing a cleaning process, a phenomenon occurs in which the diode patterns incline/slant.